Systems and methods for transmitting data via a contactless cylindrical interface

ABSTRACT

Described herein are systems and methods that create a capacitive link based on a rotating cylinder capacitor. A cylindrical rotor rotates around a shaft and maintains an air gap between the cylindrical rotor and the shaft and to create one or more air gap capacitors. A first subsystem, comprising a light detection and ranging components, is coupled to the rotor. A second sub-subsystem, comprising data analysis functions, is coupled to the shaft. The first subsystem and the second subsystem are coupled via capacitive links created by the air gap capacitors. The communication signaling utilized on the capacitive links may be bi-directional and differential signaling. The first subsystem and the second subsystem may comprise a LIDAR light detection and ranging system. The second subsystem may power the first subsystem via inductive coupling.

The present application is a continuation of and claims priority to U.S.patent application Ser. No. 15/897,814 titled “Systems and Methods forTransmitting Data via a Contactless Cylindrical Interface”, filed onFeb. 15, 2018, which is fully incorporated herein by reference.

FIELD

The present disclosure relates generally to systems and methods fortransmitting data via capacitive coupling, and more particularly theutilization of a rotating capacitor data link within a light detectionand ranging system (LIDAR).

BACKGROUND

In some electronic systems, there may be a requirement to transmit datawithin the electronic system by a wireless or non-contact (contactless)method. Possible wireless or non- contact methods may include a wirelesstechnology, an optical link, mercury electrical contact, inductivecoupling and capacitive coupling. The term “capacitive” relates toelectrical capacitance, or the property of being able to collect andhold a charge of electricity. The selected method may impact theperformance and efficiency of electronic system including, but notlimited to the frequency of operation, bandwidth, transmission speed andpower consumption. In some embodiments, such as a LIDAR system, the datamay be transferred between a stationary component and a non-stationaryrotating component.

Accordingly, what is needed are systems and methods that provide anefficient wireless or non-contact method for data transmission betweenone component of the electronic system and the rest of the electronicsystem. The one component of the electronic system may be stationaryrelative to the rest of the electronic system. Or the one component ofthe electronic system may be rotating relative to the rest of theelectronic system.

BRIEF DESCRIPTION OF THE DRAWINGS

References will be made to embodiments of the invention, examples ofwhich may be illustrated in the accompanying figures. These figures areintended to be illustrative, not limiting. Although the invention isgenerally described in the context of these embodiments, it should beunderstood that it is not intended to limit the scope of the inventionto these particular embodiments. Items in the figures are not to scale.

FIG. 1 depicts the operation of a light detection and ranging systemaccording to embodiments of the present document.

FIG. 2 illustrates the operation of a light detection and ranging systemand multi-return light signals according to embodiments of the presentdocument.

FIG. 3 depicts a LIDAR system with a rotating mirror according toembodiments of the present document.

FIG. 4A depicts a concentric cylinder capacitance according toembodiments of the present document.

FIG. 4B depicts a capacitive link between a receiver and transceiveraccording to embodiments of the present document.

FIG. 5A depicts a rotor-shaft structure of a rotor and a shaft accordingto embodiments of the present document.

FIG. 5B depicts two capacitive links providing a single directiondifferential signaling according to embodiments of the present document.

FIG. 6 depicts a flowchart for creating capacitive links according toembodiments of the present invention.

FIG. 7 depicts a system for implementing a capacitive link with customprotocols according to embodiments of the present document.

FIG. 8 depicts another system for implementing a capacitive link withcustom protocols according to embodiments of the current disclosure.

FIG. 9 depicts a simplified block diagram of a computingdevice/information handling system, in accordance with embodiments ofthe present document.

DETAILED DESCRIPTION

In the following description, for purposes of explanation, specificdetails are set forth in order to provide an understanding of theinvention. It will be apparent, however, to one skilled in the art thatthe invention can be practiced without these details. Furthermore, oneskilled in the art will recognize that embodiments of the presentinvention, described below, may be implemented in a variety of ways,such as a process, an apparatus, a system, a device, or a method on atangible computer-readable medium.

Components, or modules, shown in diagrams are illustrative of exemplaryembodiments of the invention and are meant to avoid obscuring theinvention. It shall also be understood that throughout this discussionthat components may be described as separate functional units, which maycomprise sub-units, but those skilled in the art will recognize thatvarious components, or portions thereof, may be divided into separatecomponents or may be integrated together, including integrated within asingle system or component. It should be noted that functions oroperations discussed herein may be implemented as components. Componentsmay be implemented in software, hardware, or a combination thereof.

Furthermore, connections between components or systems within thefigures are not intended to be limited to direct connections. Rather,data between these components may be modified, re-formatted, orotherwise changed by intermediary components. Also, additional or fewerconnections may be used. It shall also be noted that the terms“coupled,” “connected,” or “communicatively coupled” shall be understoodto include direct connections, indirect connections through one or moreintermediary devices, and wireless connections.

Reference in the specification to “one embodiment,” “preferredembodiment,” “an embodiment,” or “embodiments” means that a particularfeature, structure, characteristic, or function described in connectionwith the embodiment is included in at least one embodiment of theinvention and may be in more than one embodiment. Also, the appearancesof the above-noted phrases in various places in the specification arenot necessarily all referring to the same embodiment or embodiments.

The use of certain terms in various places in the specification is forillustration and should not be construed as limiting. A service,function, or resource is not limited to a single service, function, orresource; usage of these terms may refer to a grouping of relatedservices, functions, or resources, which may be distributed oraggregated.

The terms “include,” “including,” “comprise,” and “comprising” shall beunderstood to be open terms and any lists the follow are examples andnot meant to be limited to the listed items. Any headings used hereinare for organizational purposes only and shall not be used to limit thescope of the description or the claims. Each reference mentioned in thispatent document is incorporate by reference herein in its entirety.

Furthermore, one skilled in the art shall recognize that: (1) certainsteps may optionally be performed; (2) steps may not be limited to thespecific order set forth herein; (3) certain steps may be performed indifferent orders; and (4) certain steps may be done concurrently.

A. Light Detection and Ranging System

A light detection and ranging system, such as a LIDAR system, may be atool to measure the shape and contour of the environment surrounding thesystem. LIDAR systems may be applied to numerous applications includingboth autonomous navigation and aerial mapping of a surface. LIDARsystems emit a light pulse that is subsequently reflected off an objectwithin the environment in which a system operates. The time each pulsetravels from being emitted to being received may be measured (i.e.,time-of-flight “TOF”) to determine the distance between the object andthe LIDAR system. The science is based on the physics of light andoptics.

In a LIDAR system, light may be emitted from a rapidly firing laser.Laser light travels through a medium and reflects off points of thingsin the environment like buildings, tree branches and vehicles. Thereflected light energy returns to a LIDAR receiver (detector) where itis recorded and used to map the environment.

FIG. 1 depicts operation 100 of a light detection and ranging components102 and data analysis & interpretation 109 according to embodiments ofthe present document. Light detection and ranging components 102 maycomprise a transmitter 104 that transmits emitted light signal 110,receiver 106 comprising a detector, and system control and dataacquisition 108. Emitted light signal 110 propagates through a mediumand reflects off object 112. Return light signal 114 propagates throughthe medium and is received by receiver 106. System control and dataacquisition 108 may control the light emission by transmitter 104 andthe data acquisition may record the return light signal 114 detected byreceiver 106. Data analysis & interpretation 109 may receive an outputvia connection 116 from system control and data acquisition 108 andperform data analysis functions. Connection 116 may be implemented witha wireless or non- contact communication method. Transmitter 104 andreceiver 106 may include an optical lens (not shown). Transmitter 104may emit a laser beam having a plurality of pulses in a particularsequence. In some embodiments, light detection and ranging components102 and data analysis & interpretation 109 comprise a LIDAR system.

FIG. 2 illustrates the operation 200 of light detection and rangingsystem 202 including multi-return light signals: (1) return signal 203and (2) return signal 205 according to embodiments of the presentdocument. Light detection and ranging system 202 may be a LIDAR system.Due to the laser's beam divergence, a single laser firing often hitsmultiple objects producing multiple returns. The light detection andranging system 202 may analyze multiple returns and may report eitherthe strongest return, the last return, or both returns. Per FIG. 2,light detection and ranging system 202 emits a laser in the direction ofnear wall 204 and far wall 208. As illustrated, the majority of the beamhits the near wall 204 at area 206 resulting in return signal 203, andanother portion of the beam hits the far wall 208 at area 210 resultingin return signal 205. Return signal 203 may have a shorter TOF and astronger received signal strength compared with return signal 205. Lightdetection and ranging system 202 may record both returns only if thedistance between the two objects is greater than minimum distance. Inboth single and multi-return LIDAR systems, it is important that thereturn signal is accurately associated with the transmitted light signalso that an accurate TOF is calculated.

Some embodiments of a LIDAR system may capture distance data in a 2-D(i.e. single plane) point cloud manner. These LIDAR systems may be oftenused in industrial applications and may be often repurposed forsurveying, mapping, autonomous navigation, and other uses. Someembodiments of these devices rely on the use of a single laseremitter/detector pair combined with some type of moving mirror to effectscanning across at least one plane. This mirror not only reflects theemitted light from the diode, but may also reflect the return light tothe detector. Use of a rotating mirror in this application may be ameans to achieving 90-180-360 degrees of azimuth view while simplifyingboth the system design and manufacturability.

FIG. 3 depicts a LIDAR system 300 with a rotating mirror according toembodiments of the present document. LIDAR system 300 employs a singlelaser emitter/detector combined with a rotating mirror to effectivelyscan across a plane. Distance measurements performed by such a systemare effectively two-dimensional (i.e., planar), and the captureddistance points are rendered as a 2-D (i.e., single plane) point cloud.In some embodiments, but without limitations, rotating mirrors arerotated at very fast speeds e.g., thousands of revolutions per minute. Arotating mirror may also be referred to as a spinning mirror.

LIDAR system 300 comprises laser electronics 302, which comprises asingle light emitter and light detector. The emitted laser signal 301may be directed to a fixed mirror 304, which reflects the emitted lasersignal 301 to rotating mirror 306. As rotating mirror 306 “rotates”, theemitted laser signal 301 may reflect off object 308 in its propagationpath. The reflected signal 303 may be coupled to the detector in laserelectronics 302 via the rotating mirror 306 and fixed mirror 304.

As previously noted, time of flight or TOF is the method a LIDAR systemuses to map the environment and provides a viable and proven techniqueused for detecting target objects. Simultaneously, as the lasers fire,firmware within a LIDAR system may be analyzing and measuring thereceived data. The optical receiving lens within the LIDAR system actslike a telescope gathering fragments of light photons returning from theenvironment. The more lasers employed in a system, the more theinformation about the environment may be gathered. Single laser LIDARsystems may be at a disadvantage compared with systems with multiplelasers because fewer photons may be retrieved, thus less information maybe acquired. Some embodiments, but without limitation, of LIDAR systemshave been implemented with 8, 16, 32, 64 and 128 lasers. Also, someLIDAR embodiments, but without limitation, may have a vertical field ofview (FOV) up to 120 degrees with laser beam spacing as tight as 0.1degree and may have rotational speeds of 5-20 rotations per second.

The rotating mirror functionality may also be implemented with a solidstate technology such as MEMS.

B. Capacitor Coupling

In some electronic systems such as a LIDAR system, there may be arequirement to transmit data within the electronic system by a wirelessor non-contact method. Alternative wireless or non-contact methods mayinclude a wireless technology, mercury electrical contacts, opticallinks, inductive coupling and capacitive coupling. In a review of thecharacteristics of these alternatives, capacitive coupling may haveadvantages. For example, as compared to capacitive coupling, wirelesstechnologies may require 30× to 40× more power and be more expensive;inductive coupling may only provide 1/10 of the frequency oftransmission; mercury electrical contacts may not be suitable forautomotive applications and optical communication is limited to one linkof data transmission. Except for optical communications, thealternatives may have a slower data transfer than capacitor coupling.

In some embodiments, referring to the LIDAR system of FIG. 1, lightdetection and ranging components 102 may be located on a rotor and dataanalysis & interpretation 109 may be located on a shaft that is insertedin the center of the rotor. In operation, the rotor rotates around theshaft with an air gap capacitor between the rotor and the shaft. Thisstructure requires a wireless or non-contact connection. The air gapcapacitor facilitates a capacitive link, i.e., connection 116, betweenlight detection and ranging components 102 and data analysis &interpretation 109. In some other embodiments, portions of the dataanalysis functions may be located on the rotor.

Inductive coupling may be a functional solution to provide a datatransfer and power transfer between light detection and rangingcomponents 102 and data analysis & interpretation 109. Two conductorsare referred to as inductively coupled or magnetically coupled when theyare configured such that a change in current through one wire induces avoltage across the ends of the other wire through electromagneticinduction. The amount of inductive coupling between two conductors ismeasured by their mutual inductance. The voltage across an inductor isproportional to the rate of change of the applied voltage but is laggingrather than leading. Inductive coupling may generate unwanted parasiticoscillations that may limit the frequency of transmission. As previouslynoted, inductive coupling may provide a lower data transfer speed ascompared to capacitor coupling.

Capacitance is the ratio of the change in an electric charge in a systemto the corresponding change in its electric potential. That is, anelectric field causes charges in conductors to move toward the gapbetween the conductors. A simple capacitor includes two plates separatedby an insulating gap. The insulating gap may be an air gap. When voltageis applied to the capacitor terminals, electrons move from one plate tothe other, leaving one positively charged and one negatively charged.The current into a capacitor is proportional to the rate of change ofthe voltage and leads the voltage in phase when AC is applied.

Capacitive coupling is the transfer of alternating electrical signals orenergy from one segment of a circuit to another using a capacitor. Thecoupling provides a medium for the ac signals while blocking the dcenergy. Capacitive coupling may also be called AC coupling and may beused in digital circuits to transmit digital signals with a zero DCcomponent, known as DC-balanced signals. DC-balanced waveforms may beuseful in communications systems since they can be used instead ofAC-coupled electrical connections to avoid voltage imbalance problemsand charge accumulation between connected systems or components. Mostmodern line codes are designed to produce DC-balanced waveformsincluding unipolar, polar, bipolar, and Manchester encoding/decoding.

FIG. 4A depicts a concentric cylinder capacitance 400 according toembodiments of the present document. Concentric cylinder capacitance 400may comprise two concentric cylinders where a=radius of the innercylinder, b=radius of the outer cylinder and L=length of both cylinders.The capacitance air gap is equal to b−a. The capacitance of the twoconcentric cylinders is as follows:

$C = {\frac{2\; \pi \; ɛ_{o}ɛ_{r}}{\ln \left( \frac{b}{a} \right)}L}$

where ε₀ is the dielectric constant over air and ε_(r) is a relativedielectric.

The concentric cylinder capacitance 400 maintains its value if the outercylinder rotates around a stationary inner cylinder, or vice versus.

FIG. 4B depicts a capacitive link 420 between a receiver 424 andtransmitter 422 according to embodiments of the present document. Asillustrated, transmitter 422 may be a component of a PCB (printedcircuit board) located on an outer cylinder of a concentric cylinder,for example, concentric cylinder 400. Receiver 424 may be a component ofa PCB located on an inner cylinder of a concentric cylinder, forexample, concentric cylinder 400. Transmitter 422 and receiver 424 maybe capacitor coupled via air gap capacitor 426, thus creating acapacitive link between receiver 424 and transmitter 422. Outer cylinderPCB may be rotating around a stationary inner cylinder PCB or viceversa.

FIG. 4B illustrates a capacitive link supported by air gap capacitor426. This capacitive link supports a single communication link. Ifadditional communication links are desired, additional air gapcapacitors may be required. For example, two of air gap capacitor 426may provide two communication links and support either a bi-directionalor differential signaling. It follows that four of air gap capacitor 426may provide four communication links and may support bi-directionaldifferential signaling.

C. Capacitive Link

Some embodiments of non-contact coupling between components in a systemmay be based on inductive coupling. A rotating beam and fixedcylindrical beam may have two inductive coupling connections, one forthe transfer of data and one for powering the other device. Twoinductive coupling connections in differential mode may provide improvedsignal integrity as compared with a single inductive link. Improvedsignal integrity means that the signal is transferred between two pointswith improved (i.e. reduced) distortion and signal loss.

The present documents describe methods and apparatus that utilizecapacitive coupling to replace inductive coupling to enable faster datatransfer. One inductor may be replaced with two capacitors to supportdifferential signaling. Effective data rates may be 1 Gbps. With theevolution of design, future data rates may be 10 Gbps. The methods andapparatus are based on using an air gap between a rotating electrodeplate and a fixed electrode plate to create a capacitive link between aone PCB and another PCB of a system. In some embodiments of non- contactlinks, the data may be transferred utilizing a capacitive link and thepower may be transferred utilizing an inductive link. A dedicated path(capacitive link) for the data transfer may avoid noise associated withenergy transfer to provide interference cancellation.

FIG. 5A depicts the rotor-shaft structure 500 of a rotor 501 and a shaft511 according to embodiments of the present document. Rotor 501 may havea cylindrical shape and comprise a cylindrical hole in the center ofrotor 501. Shaft 511 may be positioned inside the cylindrical hole. Asillustrated, rotor 501 rotates around shaft 511. These components may beincluded in a LIDAR system. Rotor 501 may comprise rotor components 502and shaft 511 may comprise shaft components 516. Included in rotorcomponents 502 is a top PCB and included in shaft components 516 is abottom PCB. In some embodiments, rotor components 502 may comprise lightdetection and ranging components 102 and shaft components 516 maycomprise data analysis & interpretation 109 of FIG. 1.

Coupled to rotor components 502 via connections 504 are ring 506 andring 508. Ring 506 and ring 508 are circular bands located on the inneror inside surface of rotor 501 and provide electrode plate functionalityfor one side of the air gap capacitor. Coupled to shaft components 516via connections 514 are ring 510 and ring 512. Ring 510 and ring 512 arecircular bands located on the outer surface of shaft 511 and provideelectrode plate functionality for the other side of the air gapcapacitor. A capacitor C1 may be created based on a space between ring506 and ring 510. Another capacitor C2 may be created based on a spacebetween ring 508 and ring 512. The capacitance for the aforementionedcapacitors may be defined, in part, by air gap 518 and the width of thecapacitive rings 506, 508, 510 and 512. Ring 506 and ring 508 are rotorrings, and ring 510 and ring 512 are shaft rings.

Ring 506 and ring 510 are the electrode plate components of capacitor C1and ring 508 and ring 512 are the electrode plate components ofcapacitor C2. The vertical gap 520 between ring 506 and ring 508 mayimpact the performance of a capacitive link between capacitor C1 andcapacitor C2 inasmuch as the value of the vertical gap 520 may determinea level of interference between the two capacitors. One skilled in theart will recognize that rotor 501 and shaft 511 may each comprise Nrings that may support N capacitive links.

FIG. 5B depicts capacitive links 540 providing a single directiondifferential signaling according to embodiments of the present document.Capacitive links 540 may be implemented as part of the rotor-shaftstructure 500 of FIG. 5A. A multi-return light signal may be received inrotor components 502 and subsequently decoded and processed resulting insignal 542. In order to achieve a quality transfer of data to the shaftcomponents 516 with minimal noise, differential signaling may beutilized. According, signal 542 may be coupled to inverter 544 andamplifier 546. The output of inverter 544 is coupled to ring 552, whichis equivalent to ring 506 of FIG. 5A. Amplifier 546 is coupled to ring554, which is equivalent to ring 508 of FIG. 5A. Ring 552 and Ring 554may be each aligned with an air-gap to corresponding ring 556 and ring558 to create capacitors, C1 and C2, respectively. The resultingdifferential signals are coupled to differential amplifier 548 togenerate signal 550. Hence, to provide differential signaling, twocapacitive links may be required. One capacitive link is provided bycapacitor C1, and another capacitive link is provided by capacitor C2.To provide bi-directional differential signaling, four capacitive linksmay be required. The capacitors labeled “wire cap” may also be referredto as “board routing capacitor”.

Typical values for the capacitors may be as follows: C1=C2=10.9 pF;C3=2.25 pF; and C4=2.25 pF. As previously noted, capacitors C1 and C2are defined based on air gap 518 of FIG. 5A. Capacitors C3 are definedbased on vertical gap 520. In some embodiments, air gap 518 may be equalto 5 mil and vertical gap 520 may be equal to a vertical gap of 1.53 mmand a height of 6.35 mm. Based on these values, typical C1 and C2capacitors may be 10 pF to 15 PF. Larger air gap capacitors, C1 and C2,may further improve the performance of the capacitive link includinghigher transmission data rates. Future designs may achieve 50 pF to 200pF In some embodiments, a variation or tolerance of less than 20% forthe values of capacitors C1 and C2 may be required for operation of aLIDAR system. Capacitors C3 and C4 are parasitic capacitors and each ofthe C3 capacitors and each of the C4 capacitors may have differentvalues. It is desirable that the values of C3 and C4 are minimized inorder to maximum performance.

Rotor-shaft structure 500 of FIG. 5A may be configured with more thantwo rings on rotor 501 and more than two corresponding rings on shaft511. As previously discussed, bi-directional signaling or differentialsignaling may be transmitted with two rings on rotor 501 and twocorresponding rings on shaft 511. For bi-directional differentialsignaling, four rings are required on rotor 501 and four correspondingrings on shaft 511. This configuration supports four separatecommunication links. Effectively, the number of communication linksprovided by the architecture of rotor-shaft structure 500 is scalable.To add additional communication links via capacitor coupling, anadditional pair of rings may be added (i.e., stacked) on rotor 501 andshaft 511. The mechanical specification for the additional rings may bebased, in part, on air gap 518 and vertical gap 520. In summary,rotor-shaft structure 500 implements a contactless cylindrical interfacebased on capacitor coupling.

FIG. 6 depicts a flowchart 600 for creating capacitive links accordingto embodiments of the present invention. The method comprises the stepsof:

Rotating a first subsystem around a second subsystem. (step 602)

Creating a set of capacitive links between the first subsystem and thesecond subsystem based on an air gap between a set of electrodes locatedon the first subsystem and another corresponding set of electrodeslocated on the second subsystem. (step 604)

Transmitting a first set of data from the first subsystem to the secondsubsystem, and transmitting a second set of data from the secondsubsystem to the first subsystem, via the set of capacitive links. (step606)

When the number of electrodes in each set of electrodes is equal tofour, the set of capacitive links comprises four communication links.Bi-directional differential signaling may be utilized for thetransmission of data between the first subsystem and the secondsubsystem with the four communication links. The method may include:encoding and decoding bi-directional differential signals with aManchester; processing bi-directional differential signals with an errordetecting code; and powering the first subsystem by the second subsystemvia inductive coupling. The error correction code may be a cyclicredundancy check (CRC). Manchester encoding/decoding may improve thesignaling transition time and frequency of operation. In someembodiments, when the number of electrodes in each of the sets ofelectrodes is equal to N, the set of capacitive links comprises Ncommunication links.

As discussed, a system according to embodiments of the current documentmay comprises a cylindrical rotor comprising a cylindrical hole in acenter of the cylindrical rotor; one or more rotor rings that areattached to inside of the cylindrical hole of the cylindrical rotor; afirst transceiver located on and coupled to the cylindrical rotor; ashaft positioned inside the cylindrical hole in the center of thecylindrical rotor. The cylindrical rotor may rotate around the shaft.The system may also comprise: a second transceiver located on andcoupled to the shaft; one or more air gap capacitors created by an airgap between each pair of rings; one or more capacitive links coupledbetween the first transceiver and the second transceiver based on theone or more air gap capacitors.

The one or more capacitive links may create one or more correspondingseparate connections between the first transceiver and the secondtransceiver. The cylindrical rotor and the shaft may comprise Ncorresponding pairs of rings. A bi-directional differential signal istransmitted and received by the first transceiver and the secondtransceiver utilizing four capacitive links. The capacitive links mayutilize a low voltage differential signaling (LVDS) protocol, or thecapacitive links utilize Serializer/Deserializer (SERDES) interfaces.The bi-directional differential signal may be encoded and decoded with aManchester code. The bi-directional differential signal may be processedwith an error detecting code such as a cyclic redundancy check (CRC).The first transceiver and second transceiver may comprise a LIDARsystem.

D. Implementing a Capacitive Link

Two approaches to implement a capacitive link with custom protocols willbe discussed. The first approach is discussed relative to FIG.7. Thesecond approach, based on Serializer/Deserializer (SERDES) interfaces,is discussed relative to FIG. 8. FIG. 7 depicts a system 700 forimplementing a capacitive link with custom protocols according toembodiments of the present document. Characteristics of system 700include: low latency, low cost and lower max speed (^(˜)250 Mbps).System 700 comprises board 1 702, air gap capacitor 704 and board 2 706.A 750 Mhz clock a 250 Mbps data from are coupled to a clock buffer chipas illustrated in FIG. 7. The two outputs of the clock buffer chip areeach coupled to one of the two capacitors in air gap capacitor 704, andin turn, air gap capacitor 704 is coupled to board 2 706. In board 2706, the data is processed in a resonator, rectifier, and termination &level shift. The subsequent outputs are 250 Mbps differential data.

FIG. 8 depicts another system 800 for implementing a capacitive linkwith custom protocols according to embodiments of the currentdisclosure. The system uses Serializer/Deserializer (SERDES) interfacesbetween two different FPGAs (field programmable gate arrays) or customSOCs (system on a chip) to create a link without any additionalcomponents. Characteristics of this system include high latency, FPGA'sor SOC's with SERDES support; potential of higher speeds (^(˜)2 Gbpspossible); and ease of implementation.

FIG. 8 comprises top PCB 802, air gap capacitor 804 and bottom PCB 806.In operation, 6.25 Gbps data is encoded through a FPGA and capacitorcoupled via air gap capacitor 804. In turn, the signal with the encodeddata is received by a FPGA in the bottom PCB 806.

The characteristics of system 800 include: Use internal SERDES from topand bottom FPGA for AC-coupled interface; higher speed SERDES may bepreferred as AC cap acts as high-pass filter; a startup sequence for theSERDES to lock may be a concern if the signal relies on low speedpatterns; and a need to check on the lowest frequency content duringstartup. It is assumed that 8b/10b encoding can be disabled. Otherwise,8b/10b encoding or other coding schemes can also be used to maintainenough high frequency content, but there may be a need to check minimumfrequency content and accept a lower bandwidth.

E. System Embodiments

In In embodiments, aspects of the present patent document may bedirected to or implemented on information handling systems/computingsystems. For purposes of this disclosure, a computing system may includeany instrumentality or aggregate of instrumentalities operable tocompute, calculate, determine, classify, process, transmit, receive,retrieve, originate, route, switch, store, display, communicate,manifest, detect, record, reproduce, handle, or utilize any form ofinformation, intelligence, or data for business, scientific, control, orother purposes. For example, a computing system may be an opticalmeasuring system such as a LIDAR system that uses time of flight to mapobjects within its environment. The computing system may include randomaccess memory (RAM), one or more processing resources such as a centralprocessing unit (CPU) or hardware or software control logic, ROM, and/orother types of memory. Additional components of the computing system mayinclude one or more network or wireless ports for communicating withexternal devices as well as various input and output (I/O) devices, suchas a keyboard, a mouse, touchscreen and/or a video display. Thecomputing system may also include one or more buses operable to transmitcommunications between the various hardware components.

FIG. 9 depicts a simplified block diagram of a computingdevice/information handling system (or computing system) according toembodiments of the present document. It will be understood that thefunctionalities shown for system 900 may operate to support variousembodiments of an information handling system—although it shall beunderstood that an information handling system may be differentlyconfigured and include different components.

As illustrated in FIG. 9, system 900 includes one or more centralprocessing units (CPU) 901 that provides computing resources andcontrols the computer. CPU 901 may be implemented with a microprocessoror the like, and may also include one or more graphics processing units(GPU) 917 and/or a floating point coprocessor for mathematicalcomputations. System 900 may also include a system memory 902, which maybe in the form of random-access memory (RAM), read-only memory (ROM), orboth.

A number of controllers and peripheral devices may also be provided, asshown in FIG. 9. An input controller 903 represents an interface tovarious input device(s) 904, such as a keyboard, mouse, or stylus. Theremay also be a wireless controller 905, which communicates with awireless device 906. System 900 may also include a storage controller907 for interfacing with one or more storage devices 908 each of whichincludes a storage medium such as flash memory, or an optical mediumthat might be used to record programs of instructions for operatingsystems, utilities, and applications, which may include embodiments ofprograms that implement various aspects of the present invention.Storage device(s) 908 may also be used to store processed data or datato be processed in accordance with the invention. System 900 may alsoinclude a display controller 909 for providing an interface to a displaydevice 911. The computing system 900 may also include an automotivesignal controller 912 for communicating with an automotive system 913. Acommunications controller 914 may interface with one or morecommunication devices 915, which enables system 900 to connect to remotedevices through any of a variety of networks including an automotivenetwork, the Internet, a cloud resource (e.g., an Ethernet cloud, anFiber Channel over Ethernet (FCoE)/Data Center Bridging (DCB) cloud,etc.), a local area network (LAN), a wide area network (WAN), a storagearea network (SAN) or through any suitable electromagnetic carriersignals including infrared signals.

In the illustrated system, all major system components may connect to abus 916, which may represent more than one physical bus. However,various system components may or may not be in physical proximity to oneanother. For example, input data and/or output data may be remotelytransmitted from one physical location to another. In addition, programsthat implement various aspects of this invention may be accessed from aremote location (e.g., a server) over a network. Such data and/orprograms may be conveyed through any of a variety of machine-readablemedium including, but are not limited to: magnetic media such as harddisks, floppy disks, and magnetic tape; optical media such as CD-ROMsand holographic devices; magneto-optical media; and hardware devicesthat are specially configured to store or to store and execute programcode, such as application specific integrated circuits (ASICs),programmable logic devices (PLDs), flash memory devices, and ROM and RAMdevices.

Embodiments of the present invention may be encoded upon one or morenon-transitory computer-readable media with instructions for one or moreprocessors or processing units to cause steps to be performed. It shallbe noted that the one or more non-transitory computer-readable mediashall include volatile and non-volatile memory. It shall be noted thatalternative implementations are possible, including a hardwareimplementation or a software/hardware implementation.Hardware-implemented functions may be realized using ASIC(s),programmable arrays, digital signal processing circuitry, or the like.Accordingly, the “means” terms in any claims are intended to cover bothsoftware and hardware implementations. Similarly, the term“computer-readable medium or media” as used herein includes softwareand/or hardware having a program of instructions embodied thereon, or acombination thereof. With these implementation alternatives in mind, itis to be understood that the figures and accompanying descriptionprovide the functional information one skilled in the art would requireto write program code (i.e., software) and/or to fabricate circuits(i.e., hardware) to perform the processing required.

It shall be noted that embodiments of the present invention may furtherrelate to computer products with a non-transitory, tangiblecomputer-readable medium that have computer code thereon for performingvarious computer-implemented operations. The media and computer code maybe those specially designed and constructed for the purposes of thepresent invention, or they may be of the kind known or available tothose having skill in the relevant arts. Examples of tangiblecomputer-readable media include, but are not limited to: magnetic mediasuch as hard disks, floppy disks, and magnetic tape; optical media suchas CD-ROMs and holographic devices; magneto-optical media; and hardwaredevices that are specially configured to store or to store and executeprogram code, such as application specific integrated circuits (ASICs),programmable logic devices (PLDs), flash memory devices, and ROM and RAMdevices. Examples of computer code include machine code, such asproduced by a compiler, and files containing higher level code that areexecuted by a computer using an interpreter. Embodiments of the presentinvention may be implemented in whole or in part as machine-executableinstructions that may be in program modules that are executed by aprocessing device. Examples of program modules include libraries,programs, routines, objects, components, and data structures. Indistributed computing environments, program modules may be physicallylocated in settings that are local, remote, or both.

One skilled in the art will recognize no computing system or programminglanguage is critical to the practice of the present invention. Oneskilled in the art will also recognize that a number of the elementsdescribed above may be physically and/or functionally separated intosub-modules or combined together.

It will be appreciated to those skilled in the art that the precedingexamples and embodiments are exemplary and not limiting to the scope ofthe present disclosure. It is intended that all permutations,enhancements, equivalents, combinations, and improvements thereto thatare apparent to those skilled in the art upon a reading of thespecification and a study of the drawings are included within the truespirit and scope of the present disclosure. It shall also be noted thatelements of any claims may be arranged differently including havingmultiple dependencies, configurations, and combinations.

We claim:
 1. A system comprising: a cylindrical rotor that has acylindrical hole in a center of the cylindrical rotor; a transmitter; ashaft; a receiver; and a capacitive link that couples the transmitter tothe receiver via an air gap capacitor positioned between the cylindricalrotor and the shaft.
 2. The system of claim 1 further comprising: afirst ring attached to an inside surface of the cylindrical hole of thecylindrical rotor; a second ring attached to an outer surface of theshaft, wherein the shaft is positioned inside the cylindrical hole; andwherein, an air gap between the first ring and the second ring createsthe air gap capacitor.
 3. The system of claim 1, wherein data istransmitted between the transmitter and the receiver via the capacitivelink.
 4. The system of claim 1, wherein the cylindrical rotor rotatesaround the shaft.
 5. A system comprising: a cylindrical rotor comprisinga cylindrical hole in a center of the cylindrical rotor; one or morerotor rings; a first transceiver coupled to the cylindrical rotor; ashaft; one or more shaft rings; a second transceiver coupled to theshaft; one or more air gap capacitors created by an air gap between eachpair of rings; and one or more capacitive links coupled between thefirst transceiver and the second transceiver based on the one or moreair gap capacitors.
 6. The system of claim 5, wherein the one or morecapacitive links create one or more corresponding separate connectionsbetween the first transceiver and the second transceiver.
 7. The systemof claim 5, wherein the cylindrical rotor and the shaft comprises Ncorresponding pairs of rings that support N capacitive links.
 8. Thesystem of claim 5, wherein a bi-directional differential signal istransmitted and received by the first transceiver and the secondtransceiver utilizing four capacitive links.
 9. The system of claim 8,wherein the capacitive links utilize one or more of the following: a lowvoltage differential signaling (LVDS) protocol; andSerializer/Deserializer (SERDES) interfaces.
 10. The system of claim 8,wherein: the one or more rotor rings are attached to an inside surfaceof the cylindrical hole of the cylindrical rotor; the first transceiveris located on the cylindrical rotor; the shaft is positioned inside thecylindrical hole in the center of the cylindrical rotor, wherein thecylindrical rotor rotates around the shaft; and each of the one or morerotor rings is paired with a corresponding one or more shaft rings; 11.The system of claim 8, wherein the bi-directional differential signal isencoded and decoded with a Manchester code.
 12. The system of claim 8,wherein the bi-directional differential signal is processed with anerror detecting code.
 13. The system of claim 5, wherein the shaftprovides power to the cylindrical rotor via inductive coupling.
 14. Amethod comprising: rotating a cylindrical rotor around a shaft; creatinga set of capacitive links between the cylindrical rotor and the shaftbased on an air gap between a set of electrodes located on thecylindrical rotor and another corresponding set of electrodes located onthe shaft; and transmitting a first set of data from the cylindricalrotor to the shaft via the set of capacitive links.
 15. The method ofclaim 14, wherein when a number of electrodes in each of the sets ofelectrodes is equal to N, the set of capacitive links comprises Ncommunication links.
 16. The method of claim 14 further comprising:transmitting with bi-directional differential signaling over fourcapacitive links.
 17. The method of claim 16, further comprising:encoding and decoding bi-directional differential signals with aManchester code.
 18. The method of claim 14, further comprising:powering the cylindrical rotor by the shaft via inductive coupling. 19.The method of claim 14, wherein the cylindrical rotor and the shaft arepart of a LIDAR system.
 20. The method of claim 14, wherein a toleranceof the air gap capacitor is less than 20%.
 21. The method of claim 14,further comprising transmitting a second set of data from the shaft tothe cylindrical rotor.